v.
   - trip or momentarily lose one's balance. ▸walk unsteadily. 
- make a mistake or repeated mistakes in speaking.
- 
(stumble across/on/upon)
 find by chance.
n.
 an act of stumbling.
Derivative
  
    - stumbler n.
- stumbling adj.
- stumblingly adv.
 
  Etymology
  ME: from ON, from the Gmc base of stammer.